KR20170003226A - System and method of compesating brightness, display device having thereof - Google Patents

Abstract

According to the present invention, in a brightness compensating system, the brightness of a photographed test image is detected after photographing the test image displayed in a display device, a brightness compensation value for compensating a difference is generated to sample by comparing the brightness of the photographed test image with a reference brightness value, and a brightness compensation value of a current subpixel is generated based on a sampled bright-based table and a prediction coefficient to change input data based on the brightness compensation value of the current subpixel. Therefore, brightness compensation can be accurately performed even when the brightness is nonlinearly changed by a gray scale.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a luminance compensation system,

The present invention relates to a luminance compensation system and method of a display device.

2. Description of the Related Art In recent years, flat panel display devices such as a liquid crystal display device, a plasma display device, and an organic electroluminescence display device have been proposed in accordance with the demand for lightweight shortening of electronic products and portable electronic products. Among such flat panel display devices, self-emission type organic light emitting display devices are attracting attention as a next generation display device because they have a high response speed, low power consumption, high resolution and large screen.

1 is a circuit diagram schematically showing a pixel structure of a conventional organic light emitting display device.

Referring to FIG. 1, a pixel of a conventional organic light emitting display includes a switching thin film transistor ST, a driving thin film transistor DT, a capacitor C, and a light emitting element OLED. The switching thin film transistor ST is switched in accordance with a scanning signal supplied to the gate line GL to supply a data voltage Vdata supplied to the data line DL to the driving thin film transistor DT.

The driving thin film transistor DT is switched in accordance with the data voltage Vdata supplied from the switching thin film transistor ST to control the data current Idata flowing from the driving power supply Vdd to the light emitting element OLED.

The capacitor C is connected to the gate terminal of the driving thin film transistor DT and the ground line VL and stores a voltage corresponding to the data voltage Vdata supplied to the gate terminal of the driving thin film transistor DT, Thereby maintaining the turn-on state of the driving thin film transistor DT constant for one frame.

The light emitting device OLED is electrically connected to the source terminal of the driving thin film transistor DT and the ground power source Vss and emits light by the data current Idata supplied from the driving thin film transistor DT. At this time, the data current Idata flowing through the light emitting element OLED is the voltage Vgs between the gate and the source of the driving thin film transistor DT, the threshold voltage Vth of the driving thin film transistor DT and the pixel voltage Vdata. . The light emitting device OLED includes an anode electrode (not shown) connected to the driving thin film transistor DT, an organic layer formed on the anode electrode, and a cathode electrode formed on the organic layer. At this time, the organic layer may have a structure of a hole transporting layer / an organic light emitting layer / an electron transporting layer or a structure of a hole injecting layer / a hole transporting layer / an organic light emitting layer / an electron transporting layer / an electron injecting layer. In addition, the organic layer may further include a functional layer for improving the luminous efficiency and / or lifetime of the organic light emitting layer.

The pixel of the conventional organic light emitting display uses the switching of the driving thin film transistor DT according to the pixel voltage Vdata to change the magnitude of the data current idata flowing from the driving power source Vdd to the light emitting element OLED So that a predetermined image is displayed by causing the light emitting device OLED to emit light.

In the conventional organic light emitting display as described above, even if the same pixel voltage (Vdata) is supplied to each pixel, a variation in threshold voltage and channel mobility of the driving thin film transistor DT included in each pixel, And / or luminance deviation due to deterioration of the light emitting device OLED, image quality distortion phenomena such as mura or the like may occur on the screen. Such image quality distortion occurs not only in organic light emitting display devices but also in other display devices. Particularly, such image quality distortion phenomenon has a problem that the more the display device is enlarged, the more it is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a method and apparatus for generating a prediction coefficient and correcting the luminance value based on the prediction coefficient, so that even when the luminance varies non- .

In order to solve the above problems, a display device includes a display panel, a luminance controller, and a panel driver, and the display panel includes an organic light emitting display panel, a liquid crystal display panel, and an electrophoretic display panel .

The luminance correction unit generates a luminance correction value corresponding to the input data Idata, generates correction data Cdata using the generated luminance correction value and the input data Idata, and supplies the correction data Cdata to the panel driver.

Wherein the luminance correction section includes a luminance correction data generation section for correcting the luminance of the image data based on the prediction coefficient to generate the luminance correction data and a luminance correction data generation section for generating luminance correction data based on the luminance correction data and the prediction coefficient, And a data corrector for generating a correction value of the luminance, correcting the input data, and supplying the corrected data to the display panel.

Wherein the brightness correction data includes a test image generating unit that generates a plurality of test images each having a plurality of reference tone values and supplies the plurality of test images to the display device, a detection unit that detects brightness of the image data input from the image capturing unit, A correction value table generating unit for generating brightness correction value data for each test video based on the photographed data; a brightness correction table generating unit for generating brightness correction reference tables by sampling brightness correction values corresponding to positions of the plurality of reference pixels in the correction value table; And a prediction coefficient generation unit for generating a prediction coefficient for a non-linear test image whose luminance variation according to the gradation is non-linear.

At this time, the prediction coefficient generator generates a prediction coefficient based on a regression method using a least square method.

The data correction unit may include a correction value generation unit that generates a luminance correction value based on the luminance correction reference data and the prediction coefficient, and a data correction unit that corrects the data of the current sub pixel by the correction value generated by the correction value generation unit, And a data processing unit for providing the data to the data processing unit.

Meanwhile, in the present invention, when the luminance of the current sub-pixel linearly changes, the luminance correction values of the upper and lower reference gradations are linearly interpolated to correct the luminance.

In the present invention, the brightness correction values of all the pixels generated based on the brightness detection values of all the pixels detected from the test image are sampled in block units, and a plurality of brightness correction values It is possible to generate a plurality of luminance correction reference tables whose sizes are reduced by generating the reference table so that the size of the storage unit for storing the luminance correction reference table can be reduced.

Further, according to the present invention, a luminance correction value corresponding to input data is generated from a plurality of luminance correction reference tables, and the luminance value of the input data is corrected based on the prediction coefficient so that the luminance of the non-linear sub- Correction can be performed.

1 is a schematic circuit diagram of a pixel of a general organic light emitting display device.
2 is a view showing a structure of a display device according to the present invention;
3 is a block diagram showing a schematic structure of a luminance correction system according to the present invention;
4 is a block diagram showing a structure of a luminance correction data generation unit according to the present invention;
Figures 5A-5D illustrate a method of sampling the correction value table of the present invention, respectively.
6 is a block diagram showing the structure of a data correction unit according to the present invention;
7 is a flowchart showing a luminance correction method according to the present invention.

2 is a block diagram showing a schematic structure of a display device according to the present invention.

2, the display apparatus according to the present invention includes a display panel 100, a brightness control unit 200, and a panel driving unit 300. [

In the following description, the organic light emitting display panel is described as the display panel 100, but this is for convenience of description, and the present invention is not limited to such organic light emitting display panel. The present invention can be applied not only to organic electroluminescent display panels but also to all currently known flat panel display panels such as liquid crystal display panels, plasma display panels, and electrophoretic display panels.

The display panel 100 includes N gate lines GL and M data lines DL, a data line DL and a gate line Gl, which are arranged vertically to each other and define N × M sub-pixels, A plurality of first power supply lines PL1 and a second power supply line PL2 arranged in parallel, and organic light emitting devices OLED and pixel circuits PC arranged in sub-pixels, respectively.

The subpixel P may be composed of a red subpixel, a green subpixel, a blue subpixel, and a white subpixel, G) sub-pixel, and a blue (B) sub-pixel. These four sub-pixels or three sub-pixels constitute one unit pixel. In the present invention, the unit pixel may be a red (R) sub pixel, a green (G) sub pixel, a blue (B) Pixel and a blue (B) sub-pixel, but in the following description, the unit pixel is composed of a red (R) sub-pixel, a green (G) sub-pixel, a blue (B) Configuration. However, the description does not limit the unit pixel structure of the present invention, and the unit pixel of the present invention can be composed of red (R), green (G), and blue (B) sub-pixels.

The organic light emitting device OLED of each sub pixel P emits light as the pixel voltage Vdata is supplied from the panel driving unit 300 to display the image through the light emitted from each sub pixel P. [ A plurality of data lines DL are formed at regular intervals along a first direction (i.e., a horizontal direction), and a plurality of gate lines GL are formed in a second direction (i.e., vertical direction) intersecting with the first direction Are formed at regular intervals. The first power supply line PL1 is formed adjacent to each of the plurality of data lines DL and is supplied with the first driving power from the outside.

Each of the plurality of second power supply lines PL2 is formed to cross the plurality of first power supply lines PL1 and receives the second driving power from the outside. At this time, the second driving power source may have a lower potential level than the first driving power source, or may have a ground (or ground) voltage level.

The display panel 100 may include a common electrode instead of the plurality of second power lines PL2. In this case, the common electrode may be formed on the entire display region of the display panel 100 to receive a second driving power from the outside.

The organic light emitting diode OLED is connected between the pixel circuit PC and the second power supply line PL2 and emits light of a predetermined color by emitting light in proportion to an amount of data current supplied from the pixel circuit PC. The organic light emitting device OLED includes an anode electrode (or a pixel electrode) connected to the pixel circuit PC, a cathode electrode connected to the second driving power supply line PL2, and an anode electrode And an organic light emitting portion emitting red, green, blue, and white light. At this time, the organic light emitting portion may have a structure of a hole transporting layer / organic light emitting layer / electron transporting layer or a structure of a hole injecting layer / a hole transporting layer / an organic light emitting layer / an electron transporting layer / an electron injecting layer. The light emitting portion may further include a functional layer for improving the luminous efficiency and / or lifetime of the organic light emitting layer.

The pixel circuit PC responds to the scan signal SS applied to the gate line GL from the panel driver 300 and supplies the pixel voltage Vdata corresponding to the pixel voltage Vdata supplied from the panel driver 300 to the data line DL Thereby causing a data current to flow in the organic light emitting element OLED. To this end, the pixel circuit PC includes a switching transistor, a driving transistor, and at least one capacitor formed on a substrate by a thin film transistor forming process.

The switching transistor is switched according to a scanning signal SS supplied to the gate line GL to supply a pixel voltage Vdata supplied from the data line DL to the driving transistor. The driving transistor is switched according to the pixel voltage Vdata supplied from the switching transistor to generate a data current based on the pixel voltage Vdata and supplies the data current to the organic light emitting diode OLED to emit light proportional to the data current. The at least one capacitor holds the pixel voltage supplied to the driving transistor for one frame.

In the pixel circuit (PC) of each sub-pixel (P), a threshold voltage deviation of the driving transistor is generated in accordance with the driving time of the driving transistor, and as a result, the image quality may be deteriorated. Therefore, in the present invention, a compensation circuit (not shown) for compensating the threshold voltage of the driving transistor may be further included.

The compensation circuit may comprise at least one compensation transistor (not shown) and at least one compensation capacitor (not shown) formed inside the pixel circuit PC. The compensation circuit compensates the threshold voltage of each driving transistor T2 by storing the pixel voltage and the threshold voltage of the driving transistor T2 together in the capacitor during the detection period for detecting the threshold voltage of the driving transistor T2 do.

The luminance correction unit 200 generates a luminance correction value corresponding to the input data Idata input from an external system body (not shown) or a graphic card (not shown), and outputs the generated luminance correction value and the input data Idata And supplies the generated correction data Cdata to the panel driver 300. [ The specific configuration and operation of the luminance changing unit 200 will be described later in detail. Meanwhile, the flashing unit 200 may be embedded in the timing control unit 310, and in this case, may be embedded in a program form.

The wobbling unit 200 may be disposed outside the panel driving unit 300 or may be incorporated in the panel driving unit 300.

The panel driver 300 may supply a scan control signal, alignment data RGBW, and a data control signal DCS according to a timing synchronization signal TSS input from an external system body (not shown) or a graphics card (not shown) And a gate driving circuit unit for generating a scanning signal SS according to a scanning control signal SCS supplied from the timing control unit 310 and sequentially supplying the scanning signal SS to the plurality of gate lines GL 320 generates a pixel voltage Vdata based on alignment data RGBW and a data control signal DCS supplied from the timing controller 310 and a reference gamma voltage supplied from an external power supply unit And a data driving circuit 330 for supplying the data to the plurality of data lines DL.

The panel driver 300 generates a scan control signal and a data control signal based on the input timing synchronization signal TSS and generates a scan signal SS according to the scan control signal to sequentially output the scan signal SS to the gate line GL And supplies the correction data Cdata supplied from the luminance controller 200 to the data line DL by converting the correction data Cdata into the pixel voltage Vdata.

The timing control unit 310 generates a scan control signal SCS and data SCS based on a timing synchronization signal TSS such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable DE, a clock DCLK, Controls the driving timing of the gate driving circuit part 320 by the scanning control signal SCS and controls the driving timing of the data driving circuit part 330 through the data control signal DCS do.

The timing controller 310 arranges the correction data Cdata supplied from the luminance controller 200 in the order of red, green, blue, and white so as to be suitable for driving the display panel 100, To the data driving circuit portion 330. [

The gate driving circuit unit 320 generates a scanning signal SS according to a gate control signal SCS supplied from the timing controller 310 and sequentially supplies the scanning signal SS to the plurality of gate lines GL.

The data driving circuit 330 converts the alignment data RGBW into an analog pixel voltage Vdata using a plurality of reference gamma voltages in accordance with the data control signal DCS, (DL).

As described above, in the display apparatus of the present invention, the luminance correction value corresponding to the input data (Idata) is generated using the luminance stepping unit (200) to correct the luminance value of the input data (Idata) , It is possible to improve the image quality distortion phenomenon caused by the luminance non-uniformity characteristics of the sub-pixels P, respectively.

FIG. 3 is a block diagram schematically showing the flashing unit 200. FIG. As shown in Fig. 3, the luminance-leveling unit 200 captures a picture of a test image supplied to the display device 100 and displayed on the display device, and corrects the luminance of the image data of the input image- A brightness correction data generation unit 210 for generating brightness correction data based on the brightness correction data generated by the brightness correction data generation unit 210 and generating brightness correction values based on the brightness correction data, A data correction unit 230 for correcting input data Idata and supplying correction data Cdata of the corrected current sub-pixel to a timing control unit 310 of the panel driving unit 300, And a storage unit 250 for storing the luminance correction data generated by the luminance correction unit 210 and the correction data Cdata generated by the data correction unit 230.

As shown in Fig. 2, the display device 100 generates a data signal corresponding to input data input from the outside and a display panel including a plurality of pixels defined by a plurality of data lines and a plurality of gate lines And a panel driver 300 for supplying the pixels to each pixel.

Each of the plurality of pixels is a unit pixel composed of red (R), green (G), and blue (B) subpixels or a subpixel of red (R), green (G), blue (B), and white And may be a unit pixel made up of pixels.

The input data may be three-color input data (RGB) to be supplied to each pixel or four-color input data (RGBW). Here, the white W input data W in the four-color input data RGBW are set to the minimum gradation values of the first red (R), green (G) and blue (B) data, ), Green (G), and blue (B) input data is a tone value obtained by subtracting the white (W) input data from the tone values of the first red (R), green Respectively. In the following description, each pixel is a unit pixel composed of red (R), green (G), blue (B) and white (W) sub-pixels, do.

The luminance correction data generation unit 210 generates luminance correction data by generating a correction value table by detecting luminance of the photographed test image, generating a prediction coefficient after sampling the generated table, and generating luminance correction data based on the generated prediction coefficient. The data correction unit 230 corrects the input data Idata input to the current sub-pixel based on the luminance correction data generated by the luminance correction data generation unit 220. [

4 is a block diagram showing the luminance correction data generation unit 210 shown in FIG.

4, the luminance correction data generation unit 210 according to the present invention includes a test image generation unit 212, a luminance value detection unit 212, a control unit 213, a correction value table generation unit 214, A sampling unit 216 and a prediction coefficient generation unit 218. [

The test image generating unit 212 generates a plurality of test images such as the first to fourth test images having different reference tone values and sequentially outputs input data of one frame corresponding to each of the generated first to fourth test images To the display device 100 as shown in FIG. For example, the test image generating unit 212 generates a first test image having 32 reference tone values, a second test image having 64 reference tone values, a third test image having 128 reference tone values, and 255 Generates a fourth test image having a reference tone value, and sequentially supplies each of the generated first to fourth test images to the display device 100.

In the above description, the first test image having 32 standard gradation values, the second test image having 64 standard gradation values, the third test image having 128 standard gradation values, and the reference gradation value of 255 The present invention is not limited to such a specific number of test images but may use less than four test images or more than four test images.

As described above, the first to fourth test images are sequentially displayed on the display panel of the display device 100 in accordance with the input data of one frame as the first to fourth test images are supplied to the display device 100.

As shown in FIG. 2, the image capturing means 110 photographs each of the first to fourth test images sequentially displayed on the display panel 100, And transmits the photographed data to the luminance value detection section 212. [ At this time, the image photographing means 112 may be a camera or a CCD.

The control unit 213 controls the overall operation of the luminance correction data generation unit 210. That is, the control unit 213 controls operations of the test image generating unit 212, the luminance value detecting unit 212, the correction value table generating unit 214, the sampling unit 216, and the prediction coefficient generating unit 218 .

The brightness value detection unit 212 detects the brightness detection values of each pixel for each of the first to fourth test images based on the photographic data for each of the first to fourth test images supplied from the image capturing unit 110, To the value table generating unit 214.

The correction value table generation unit 214 compares the luminance detection value of each pixel for each of the first to fourth test images supplied from the luminance value detection unit 212 with the reference luminance value set for each pixel, The brightness correction value of each pixel for each of the first to fourth test images is generated for each pixel.

 That is, the luminance correction value is reflected (for example, to be added and subtracted) in the input data of each pixel so that the luminance detection value becomes the reference luminance value.

The correction value table generation unit 214 maps the luminance correction values of the respective pixels of the first to fourth test images so as to correspond to the pixel positions and generates a correction value table for each of the first to fourth test images do. At this time, the correction value table for each of the first to fourth test images has the same size as the resolution of the display panel, and is separately generated for each of the plurality of test images.

The sampling unit 216 samples the brightness correction value of the reference pixel set in the correction value table of each of the first to fourth test images generated by the correction value table generating unit 214, And generates a luminance correction reference table for each of the first to fourth test images by individually mapping the reference luminance correction values of the reference pixels for each of the first to fourth test images, 250). That is, the sampling unit 216 generates a luminance correction reference table for each of the first to fourth test images, which are reduced in size of the correction value table of each of the first to fourth test images, .

For example, the storage unit 250 may include a luminance correction reference table of the first test image to which the reference luminance correction values of the reference pixels for the 32 reference tone values are mapped, a reference luminance reference table for the reference tone values of 64, A luminance correction reference table of the second test image to which the luminance correction values are mapped, a luminance correction reference table of the third test image to which the reference luminance correction values of the reference pixels with respect to the reference tone values of 128 are mapped, Each of the luminance correction reference tables of the fourth test image to which the reference luminance correction values of the respective reference pixels are mapped. At this time, the storage unit 250 may be a memory.

The sampling unit 216 may sample the correction value table by various methods. 5A to 5D are views showing a sampling method according to the present invention. The method shown in the figure is a diagram showing some examples of sampling, and the sampling method of the present invention is not limited to the method shown in the drawings.

5A, the sampling unit 216 divides the display area of the display panel into a plurality of blocks BL each consisting of N × N pixels, In each of the correction value tables, the luminance correction values mapped to the positions of the reference pixels RP set in the N × N pixels included in each of the blocks BL are sampled, Generates a luminance correction value, and generates a luminance correction reference table for each of the first to fourth test images by individually mapping the reference luminance correction values for each block of the first to fourth test images, and stores the generated luminance correction reference table in the storage unit 250.

In this method, the sampling unit 216 down-samples each of the correction value tables of the first to fourth test images to generate the luminance correction reference table of each of the first to fourth test images, The size of the storage unit 250 storing the correction reference table can be reduced. For example, when each block BL is composed of 4 × 4 pixels, the reference pixel RP may be set as a pixel (hatched pixel) located in the first row and the first column of each block BL. In this case, in the reference correction value table of each of the first to fourth test images, the sampling unit 216 samples the first to (n-1) th pixels mapped to positions of the 4i-3 (i is a natural number) 4 samples each luminance correction value of each test image. When each block BL is set to 4x4 pixels, the size of the storage unit 256 for storing the one luminance correction reference table may be reduced to 1/16 of one correction value table.

5B, the sampling unit 216 divides the display area of the display panel into a plurality of blocks BL each having N × N pixels, The brightness correction value of each of the first to fourth test images mapped to the positions of the plurality of reference pixels RP located in the diagonal direction among the NxN pixels included in each block BL is sampled by the first -4 Generate the reference luminance correction value for each block of the test image. Thereafter, the reference luminance correction values for each block of the first to fourth test images are individually mapped to generate the luminance correction reference table for each of the first to fourth test images, and the generated luminance correction reference table is stored in the storage unit 250.

As a result. The sampling unit 216 generates a reference luminance correction value for each of the first to fourth test images for each of the four pixels located in the diagonal direction for each block BL. When each of the blocks BL is set to 4 × 4 pixels, the size of the storage unit 250 storing the one luminance correction reference table may be reduced to 1/4 of one correction value table.

5C or 5D, the sampling unit 216 divides the display area of the display panel into a plurality of blocks BL each having N × N pixels, A plurality of reference pixels RP located in one horizontal direction (HL1, HL5, HL9, ..) or one vertical direction (VL1, VL5, VL9, ..) And generates a reference brightness correction value for each block of the first to fourth test images by sampling the brightness correction values of the first to fourth test images mapped to the first to fourth test images. Thereafter, the reference luminance correction values for each block of the first to fourth test images are individually mapped to generate the luminance correction reference table for each of the first to fourth test images, and the generated luminance correction reference table is stored in the storage unit 250.

As a result, the sampling unit 216 outputs four pixels HL1, HL5, HL9,... Or one vertical direction VL1, VL5, VL9, By generating the reference luminance correction values of the first to fourth test images for each block BL, it is possible to prevent image quality distortion phenomena such as smear defects locally generated in the remaining pixels except the reference pixel RP of each block BL Can be compensated.

As a result, the sampling unit 216 samples four luminance correction values for N or fewer reference pixels set in each block BL consisting of N × N pixels to generate four reference luminance correction values.

The prediction coefficient generation unit 218 generates a prediction coefficient of the luminance correction value for the first to fourth test images of each pixel. That is, when generating the luminance correction value of each sub-pixel based on the input data of each sub-pixel, the prediction coefficient generates a prediction coefficient for the luminance correction value. The reason for generating the prediction coefficient is as follows.

When generating the luminance correction values of gradations other than the reference gradation, the luminance correction values of the corresponding gradation are generated using the luminance correction reference tables of the upper and lower reference gradations. When the luminance variation according to the gradation is linear, the luminance correction value of the corresponding gradation can be generated by linearly interpolating the luminance correction values of the luminance correction reference table of the upper and lower reference gradations.

However, since the luminance variation according to the gradation displayed on the display device is nonlinear, accurate luminance correction values for gradations other than the reference gradation can not be obtained by linear interpolation, and as a result, And distortion of image quality can not be completely solved.

In order to solve such a problem, for example, in addition to the reference tone value of 32, the reference tone value of 64, the reference tone value of 128, and the reference tone value of 255, reference tone values of 48, reference tone values of 96, (For example, eight reference gradation values or sixteen reference gradation values) is added to generate a test image corresponding to the reference gradation value, and then the test image is displayed on the screen It is possible to precisely generate the luminance correction value by linear interpolation by detecting the luminance value of the test image and generating the luminance correction reference table of the reference gradation. However, in this case, the calculation for generating the luminance correction reference table becomes complicated due to addition of the reference tone value, and the capacity of the storage unit 250 for storing the luminance correction reference table must increase.

In the present invention, after the generation of the prediction coefficient for each pixel, the luminance correction value of each pixel is generated based on the prediction coefficient, so that it is not necessary to add the reference tone value.

The prediction coefficient generation unit 218 generates prediction coefficients for each gray level, and stores the prediction coefficients in the storage unit 250. The stored prediction coefficients also generate a luminance correction value for each gradation of each sub-pixel, together with the luminance correction value of the luminance correction table stored in the storage unit 250. [

The prediction coefficient generation unit 218 can generate prediction coefficients in various ways. For example, the prediction coefficient generation unit 218 generates a prediction coefficient according to a regression method using a least square method, for example, by the following equation (1).

At this time,?,?, And X may be represented by a matrix as shown in the following Equation 2-4, respectively.

Here, a, b, and c are prediction coefficients for the gradation of each pixel, respectively.

Here, Z1 ... Zm is a luminance correction reference table.

Here, x1 ... xm is a reference luminance correction value for each block mapped to the position of the block including the corresponding pixel in the luminance correction table of the lower reference gradation of the pixel, and y1 ... ym is a reference luminance correction value for each block, Is a reference luminance correction value for each block mapped to the position of the block including the corresponding pixel in the luminance correction table.

The prediction coefficient generation unit 218 generates prediction coefficients by the least squares method using the matrix as described above, and stores the generated prediction coefficients in the storage unit 250. [

The generation of a prediction coefficient according to the above equation is an example for generating a prediction coefficient. In the present invention, a prediction coefficient can be generated according to various equations known at present.

6 is a block diagram showing the structure of the data correcting unit 230. As shown in FIG. As described above, the data correction unit 230 generates a luminance correction value based on the luminance correction data generated by the luminance correction data generation unit 210 and stored in the storage unit 250, and the prediction coefficient, And supplies the corrected correction data Cdata of the corrected current sub-pixel to the timing controller 310 of the panel driver 300. [

As shown in FIG. 6, the data correction unit 230 includes a correction value generation unit 232 and a data processing unit 234.

The storage unit 250 stores a plurality of test image-based brightness correction reference tables and prediction coefficients generated by each of a plurality of test images each having a plurality of different reference tone values for each of a plurality of blocks, Is stored. For example, the storage unit 250 stores luminance correction reference tables T1, T2, T3, and T4 for each of the first through fourth test images generated by the luminance correction data generation unit 210. [ In the storage unit 250, prediction coefficients of the pixels generated by the luminance correction data generation unit 210 are stored.

The correction value generation unit 222 generates the correction value for each of the sub pixels in units of pixels by using the luminance correction reference tables T1, T2, T3, and T4 of the first to fourth test images stored in the storage unit 250, Reads the reference luminance correction values for one or two blocks corresponding to the input data, generates luminance correction values (Pcv) for the respective sub-pixels by using the prediction coefficients, (Pcv) to the data processing section 23.

Specifically, the correction value generator 232 generates brightness correction reference tables T1 and T2 of each of the first to fourth test images based on input data of each pixel input from the outside, that is, input data of each of the sub- , T3, and T4), or a reference luminance correction value for each block is read out for each sub-pixel, or a reference luminance correction value for each sub-pixel is read from the sub-reference gray- The reference luminance correction value for each block is read. Thereafter, the correction value generator 232 interpolates the reference luminance correction values for one or two blocks read for each sub-pixel by a prediction coefficient to generate a luminance correction value Pcv of each sub-pixel.

Each pixel is composed of red, green, blue, and white sub-pixels, the input data of the red sub-pixel input to the current pixel is a gray-scale value of 0, the input data of the green sub- A method of generating the luminance correction value Pcv, for example, when the input data has a gray-scale value of 64 and the input data of the white sub-pixel has a gray-scale value of 160 will be described concretely.

In the case of the red sub-pixel, since the input data of the red sub-pixel has a value of 0, it does not have the lower and lower reference gray-scale values. However, by applying the prediction coefficient as shown in Equation 5 below, Value < RTI ID = 0.0 > (Pcv) < / RTI >

Here, z is the luminance correction value (Pcv), and a, b, and c are prediction coefficients. X is a reference brightness correction value for each block mapped to a block including a current pixel in a brightness correction reference table generated from a test image having a lower reference gray value of the corresponding gray level, Is a reference luminance correction value for each block mapped to the position of the block including the current pixel in the luminance correction reference table generated from the test image.

In the case of the red sub-pixel, since the input data of the red sub-pixel is a value of 0, the luminance correction value Pcv of c is generated because it does not have the lower and lower reference gradation values.

In the case of the green sub-pixel, since the input data of the green sub-pixel has the gray-scale value of 48, the first luminance-adjustment reference table T1 generated from the test image having the 32 reference gray- The reference luminance correction value for each block mapped to the position of the block including the current pixel is read, and at the same time, the luminance correction reference table for the second test image generated from the test image having 64 reference gray- The correction value generation unit 232 reads the reference luminance correction value for each block mapped to the current pixel position in step T2. Next, a prediction coefficient is read from the storage unit 250 and a luminance correction value Pcv of the green sub-pixel is generated according to Equation (5).

In the case of the blue sub-pixel, since the input data of the blue sub-pixel has the tone value of 64, the current pixel is included in the luminance correction reference table T2 of the second test image generated from the test image having the reference tone value of 64 The reference luminance correction value for each block mapped to the position of the block is read. Next, a prediction coefficient is read from the storage unit 250 and a luminance correction value Pcv of the green sub-pixel is generated according to Equation (5).

In the case of the white sub-pixel, since the input data of the white sub-pixel has a gray-scale value of 160, it is mapped to the position of the block including the current pixel in the brightness correction reference tables T3 and T4 of the third and fourth test images The reference brightness correction value for each block is read. Next, a prediction coefficient is read from the storage unit 250 and a luminance correction value Pcv of the green sub-pixel is generated according to Equation (5).

The correction value generation unit 232 generates a luminance correction value Pcv for each of all the sub-pixels according to the input data to be supplied to each sub-pixel of the display panel, and supplies the luminance correction value Pcv to the data processing unit 234.

Referring again to FIG. 7, the data processing unit 234 receives the luminance correction value Pcv of the current sub-pixel generated by the correction value generation unit 232 in the input data Idata of the current sub- Pixel to correct the input data Idata of the current sub-pixel, and supplies the correction data Cdata of the corrected current sub-pixel to the panel driver. For example, the data processing unit 234 can generate the correction data Cdata of the current sub-pixel by correcting the input data Idata of the current sub-pixel and the luminance correction value Pcv of the current sub- .

Hereinafter, a method of correcting the brightness of the display apparatus using the above-described apparatus will be described.

7 is a flow chart showing a method of correcting the luminance of the display apparatus according to the present invention.

7, first, a first test image having a first reference tone value such as a tone value of 32 is generated to display a first test image on a display panel of the display device 100, The first test image displayed by the first test image is photographed to generate first image data (S101).

Thereafter, the brightness value of the first test image for each pixel of the display panel is detected based on the first image data, and the brightness correction value of the brightness value of the detected first test image for each pixel is generated, (Step S102).

Subsequently, a luminance correction value corresponding to the position of the reference pixel set in each block BL divided on the display panel in the correction value table of the first test image is sampled to generate a reference luminance correction value for each block of the first test image A brightness correction reference table of the first test image including the generated reference brightness correction value for each block is generated and stored in the storage unit at step S103.

Then, based on the regression method using the least squares method, a prediction coefficient for the luminance correction value of the first test image is generated and stored in the storage unit (S104).

Subsequently, for example, for the second test image having a gray level value of 64, the third test image having 128 gray level values, and the fourth test image having 255 gray level values, S104-S104 are repeated to repeat the second -4 The luminance correction reference table and the prediction coefficient of the test image are generated and stored in the storage unit.

In the above description, the luminance correction reference table and the prediction coefficient are generated for the four test images. However, the luminance correction reference table and the prediction coefficient are also generated for test images of less than four or more than four test images, . ≪ / RTI >

Thereafter, using one or two brightness correction reference tables T1, T2, T3, and T4 of each of the first to fourth test images stored in the storage unit, one or two After reading the reference luminance correction value and the prediction coefficient for each block, the luminance correction value of the current sub-pixel is generated using the reference luminance correction value for each block (S105).

Specifically, when the tone value of the input data has a tone value of 0, the luminance correction value of the current sub-pixel is generated with a constant value.

When the tone value of the input data is equal to any one of the plurality of reference tone values that are the reference of the luminance correction value, the luminance correction reference tables (T1, T2, T3, T4) corresponding to the tone values of the input data ), Which is mapped to the position of the block including the current pixel. When a tone value of the input data is different from a plurality of reference tone values, a table corresponding to lower and upper reference tone values of the tone value of the input data among the luminance correction reference tables (T1, T2, T3, T4) The luminance correction value Pcv of the current sub-pixel is generated based on the reference luminance correction value and the prediction coefficient for each block mapped to the position of the block including the current pixel.

Subsequently, the input data Idata of the current sub-pixel is corrected by reflecting the luminance correction value Pcv of the current sub-pixel generated in the input data Idata of the current sub-pixel, and the correction data Cdata ) To the panel driver so as to display the image whose luminance is corrected on the screen (S106, S107).

As described above, in the present invention, the luminance is corrected by generating a reference luminance correction value and a prediction coefficient for each reference gradation and generating a luminance correction value of the sub-pixel based on the reference luminance correction value and the prediction coefficient. Therefore, it is possible to prevent the luminance of the sub-pixel from becoming non-uniform even when the luminance change according to the gradation is nonlinear.

In particular, in the present invention, it is possible to perform luminance correction even when the minimum gradation or the maximum gradation is used such as black or white. For example, when the luminance correction is performed by linear interpolation, the lower reference gradation value and the upper reference gradation value must be linearly interpolated. However, since black or white does not have a lower mood gradation or higher reference gradation, The luminance correction could not be performed for white or white. However, in the present invention, since the luminance correction is performed by the prediction coefficient, the luminance can be corrected even in the case of the minimum gradation or the maximum gradation, thereby solving the problem of the luminance unevenness.

Also, the present invention can be applied to a case where the luminance change according to the gradation is linear. In this case, in the luminance correction reference tables T1, T2, T3, and T4 stored in the storage unit 250, the lower reference gradation value and the upper reference gradation value of the gradation value of the input data are linearly interpolated So that the luminance can be corrected.

Further, in the present invention, after the correction value generator 232 determines whether the luminance change of the input data is linear or non-linear, in a linear case, the luminance is corrected by linearly interpolating the lower reference tone value and the upper reference tone value, , The luminance correction is carried out by the prediction coefficient, whereby accurate luminance correction can always be performed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, although the organic electroluminescence display panel is exemplified as the display panel in the above-mentioned detailed description, the display panel of the present invention is not limited to such an organic electroluminescence display panel but may be a liquid crystal display panel, a plasma display panel, And may be applied to all currently known types of display panels, such as electrophoretic display panels.

Further, in the above-described detailed description, it is described that the luminance correction section is arranged separately from the timing control section. However, the luminance correction section may be incorporated in the timing control section, and in this case, it may be embedded in a program form.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the embodiments described above are illustrative and do not limit the scope of the invention. Therefore, the scope of the present invention should be defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention. .

100: display device 200:
210: luminance correction data generation unit 230:
250: storage unit 300:
310:

Claims (18)

A test image generating unit that generates a plurality of test images including a plurality of reference tone values and supplies the generated test images to a display device;
Image capturing means for capturing each of a plurality of test images displayed on the display device and generating shooting data for each of the test images;
A correction value table generating unit for generating brightness correction value data for each test image based on the shooting data for each test image; And
And a prediction coefficient generator for generating a prediction coefficient for the test image. 2. The luminance correction system according to claim 1, wherein the prediction coefficient is a prediction coefficient for a non-linear test image in which the luminance change according to the gradation is non-linear. The luminance correction system according to claim 1, wherein the prediction coefficient generator generates a prediction coefficient based on a regression method using a least square method. The method according to claim 1,
A detecting unit for detecting the luminance of the photographic data input from the image photographing unit; And
And a sampling unit for generating a luminance correction reference table by sampling luminance correction values corresponding to positions of each of the plurality of reference pixels in the correction value table. 5. The luminance correction system of claim 4, further comprising a storage unit for storing the luminance correction reference table and the prediction coefficients. 6. The method of claim 5,
A correction value generation unit for generating a luminance correction value based on the luminance correction reference data and the prediction coefficient stored in the storage unit; And
And a data processing unit for correcting the data of the current sub-pixel according to the correction value generated by the correction value generation unit and providing the corrected data to the display device. 7. The luminance correction system of claim 6, wherein the correction value generator linearly interpolates the luminance correction values of the upper and lower reference gradations when the luminance of the current sub-pixel linearly changes. A display panel on which an image is displayed;
A panel driver for applying a signal to the display panel to implement an image;
A luminance correction data generation unit for generating luminance correction data by correcting the luminance of the video data based on the prediction coefficient; And
And a data correction unit that generates a luminance correction value based on the luminance correction data generated by the luminance correction data generation unit, corrects the input data input to the current sub-pixel, and supplies the correction data to the panel driving unit. The apparatus of claim 8, wherein the luminance correction data generation unit comprises:
A test image generating unit that generates a plurality of test images including a plurality of reference tone values and supplies the generated test images to a display device;
Image capturing means for capturing each of a plurality of test images displayed on the display device and generating shooting data for each of the test images;
A correction value table generating unit for generating brightness correction value data for each test image based on the shooting data for each test image; And
And a prediction coefficient generator for generating a prediction coefficient. 10. The display apparatus of claim 9, wherein the prediction coefficient is a prediction coefficient for a non-linear test image in which the luminance variation according to the gradation is non-linear. The apparatus of claim 8,
A correction value generation unit for generating a luminance correction value based on the luminance correction reference data and the prediction coefficient; And
And a data processing unit for correcting the data of the current sub-pixel according to the correction value generated by the correction value generation unit and providing the data to the display device. The display device according to claim 8, wherein the display panel includes an organic light emitting display panel, a liquid crystal display panel, a plasma display panel, and an electrophoretic display panel. A step of photographing a test image displayed on a display device;
Generating a correction value table of the test image based on the data of the captured test image;
Generating a luminance correction reference table by sampling a luminance correction value of the correction value table; And
And generating a prediction coefficient for the luminance correction value of the test image in which the luminance varies nonlinearly according to the gradation. 14. The luminance correction method of claim 13, wherein the prediction coefficient is a prediction coefficient for a non-linear test image in which the luminance change according to the gradation is non-linear. 14. The method of claim 13,
Generating a luminance correction value of the sub-pixel by the reference luminance correction value and the prediction coefficient; And
And correcting the input data of the current sub-pixel by reflecting the luminance correction value of the sub-pixel generated in the input data of the sub-pixel. The method as claimed in claim 13, wherein the step of generating the correction value table comprises the step of detecting a luminance value of the test image based on the data of the test image and generating a luminance correction value of the luminance value of the detected test image . 14. The method of claim 13,
Further comprising the step of determining whether the brightness of the test image is linear or non-linear according to the gradation. The brightness correction method according to claim 17, wherein the brightness correction values of the upper and lower reference gradations are linearly interpolated when the brightness of the gradation of the test shape linearly changes.

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